The invention relates to a valve, especially for shut-off and regulating means, having a flat, piston-like or spherical valve body made of a metal or nonmetallic material with at least one hard coating applied to the valve body, and a method for applying hard coatings to the valve body.
In high-quality faucets (e.g., single-lever mixing faucets), polished ceramic disks sliding one on the other are used as valve bodies for shutting off and controlling liquids and the like. To minimize wear on these disks or valve bodies and the friction involved in operating the faucets, one of the manufacturing steps consists in lubricating them superficially with installation grease. This grease is consumed in a few weeks by the flow of the liquid and the shifting of the ceramic disks by the operation of the faucet, so that ultimately all that is left as lubricant is the liquid being controlled by the disks. This as a rule is insufficient. In the ungreased state the static friction coefficient is often so high that, in addition to a general stiffness of operation (high static friction coefficient), the disks have been observed to stick. Then, if force is applied, the wear on the disks increases drastically and the faucet becomes unusable (U.S. Pat. Nos. 3,533,436; 4,685,487; 3,834,416). It is known that hard, amorphous, hydrogenous carbon coatings (a-C:H) in pure form or with admixtures of other elements have low dynamic friction coefficients. In general, nothing is said EP No. 0 087 836, to which U.S. Pat. No. 4,525,417 correspondent about the static friction coefficient. Furthermore, the deposit of siliceous and carbonaceous coatings of organic silicon compounds by means of a plasma has been disclosed in U.S. Pat. No. 3,822,928, European Pat. No. 0 150 878, and French Pat. No. 0.230.188.